As the information application rapidly developing, various types of data storage devices, such as flash memory stick or memory cards, are developed. The data storage devices based on flash memory is among the most popular. To enhance the capability and improve the characteristics of flash memory sticks or memory cards, such as reading product ID or accelerating data access, the application at the host end usually transmits commands for activating specific application or executable applications to the controller of the memory card in order to execute the commands or the executable applications.
The current operating system uses the logic block area (LBA) mode to access peripheral storage devices and the diverse applications are developed for the storage devices.
FIG. 1 shows a schematic view of a conventional LBA mode. As shown in FIG. 1, the host end, such as PC 10, includes an application program (AP) 12 to transmit LBA transmission unit 31 having a header 33 and data sector 35 through transmission interface 30 to storage device 20. Transmission interface 30 can be a USB interface. Storage device 20 includes a controller 22 and a memory 24. Header 33 of LBA transmission unit 31 includes an LBA address for designating the storage address for the data of data sector 35.
The commands used by the diverse applications include two types, proprietary commands and through commands. USB transmission protocol uses SCSI command subset for data access; therefore, the proprietary commands can use the reserve field so that the controller of the storage device can differentiate the proprietary commands from the normal data. On the other hand, through commands uses the characteristics of file system to generate a plurality of files of specific size in the protected area of the storage device so that these files will not be overwritten or deleted. Also, these files are used to edit own through commands for transmission to the storage device. Because the through command is also a part of the data, the operating system will not filter out, i.e., wrapping the through command in a data format.
However, a major drawback of the conventional technology is that the reserve field used by the proprietary commands is considered as an invasion condition by the operating system. Therefore, the non-standard commands are all filtered out and the applications cannot be developed.
Another drawback of the conventional technology is that the through commands can only be realized in known file systems, such as FAT16, FAT 32. The development time is also longer for the application using through commands because the application must develop appropriate file behavior for the file system so that the through command can be edited into the files.
Therefore, it is imperative to devise a method for protecting proprietary commands to meet the standard transmission regulation and to allow the data and specific proprietary commands will not be filtered out by the operating system to solve the drawbacks of the conventional technology.